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'''1. gconf value''', that allow power users to change voltage, at which device shutdowns to any arbitrary value. | '''1. gconf value''', that allow power users to change voltage, at which device shutdowns to any arbitrary value. | ||
- | This is | + | This is preffered solution, as some devices are more like to have problems with GSM chip restarting at low voltage, even around '''EDV1''' 3248 mV. People with such problems, that preffer GSM stability over calibration, could bump voltage treeshold, to avoid problems. OTOH, people with less picky devices and/or dual-cell setups, could decrease limit, getting more from their batteries. |
- | This method can be also augmented by solution 2, for "default" shutdown | + | This method can be also augmented by solution 2, for "default" shutdown treeshold. |
'''1.a gconf value plus guard time''' use a timer plus frequent probing to ensure the voltage stays below the threshold set by gconf. This is the recommended method since the whole shutdown shouldn't get triggered by sub-second "brownouts" caused by power consumption spikes. A suggested guard time is 30..60s, a suggested sampling frequency for voltage is 1/s, though the hardware has limited support for such high sampling frequencies of voltage - further evaluation needed. Other alternative concepts like average over moving window (again window size: 30..60s) might be worth to consider. | '''1.a gconf value plus guard time''' use a timer plus frequent probing to ensure the voltage stays below the threshold set by gconf. This is the recommended method since the whole shutdown shouldn't get triggered by sub-second "brownouts" caused by power consumption spikes. A suggested guard time is 30..60s, a suggested sampling frequency for voltage is 1/s, though the hardware has limited support for such high sampling frequencies of voltage - further evaluation needed. Other alternative concepts like average over moving window (again window size: 30..60s) might be worth to consider. | ||
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'''EDV1''' flag can be read from ''/sys/class/power_supply/bq24150a-0/registers'' address 0x55 0x0A, divided by 2. | '''EDV1''' flag can be read from ''/sys/class/power_supply/bq24150a-0/registers'' address 0x55 0x0A, divided by 2. | ||
- | '''2.a''' In case of '''EDV1''' flag being not available'''*''', fallback to using 3150 mV as shutdown | + | '''2.a''' In case of '''EDV1''' flag being not available'''*''', fallback to using 3150 mV as shutdown treeshold. Rationale: 3150 mV shouldn't cause GSM chip restarts on devices, where 3248 mV haven't caused it already. |
It doesn't guarantee calibration, as it require 15 seconds *straight* below 3248 mV (EDV1 voltage), and 3150 mV might be just momentary low voltage spike. But, it is better than current implementation, which permits calibration *ever* - and, after all, it is just theoretical fallback for hyphotetical, non-existing kernel. | It doesn't guarantee calibration, as it require 15 seconds *straight* below 3248 mV (EDV1 voltage), and 3150 mV might be just momentary low voltage spike. But, it is better than current implementation, which permits calibration *ever* - and, after all, it is just theoretical fallback for hyphotetical, non-existing kernel. |
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